The present invention relates to a control valve.
The terms "upward" and "downward" and like terms as used herein and in the appended claims are merely intended to express the position relation between the components of the control valve as arranged in the drawings showing the embodiment to be described below. These terms should not be interpreted as expressing the absolute "up-down" relation in the state in which the control valve is used.
The control valve comprises a valve body having a fluid channel and a valve seat; a valve operating part; a valve stem supporting member having its upper end fixed to the valve operating part and its lower end fixed to the valve body respectively; a valve stem penetrating the valve stem supporting member and having its upper end part connected to the valve operating part and its lower end part entering the valve body, the valve stem being movable upwardly or downwardly by means of the valve operating part; and a valve element attached to the lower end of the valve stem. The valve element is moved upward or downward by moving the valve stem upward or downward. The valve element is brought into contact with and seated in the valve seat to close the fluid channel as it is moved downward. The valve element is detached from the valve seat to open the fluid channel as it is moved upward.
Conventionally, this type of control valve has the valve stem integrally formed by metal.
However, in the conventional control valve having the entire valve stem integrally formed by metal, when a fluid in a low temperature or in a high temperature flows through the fluid channel of the valve body, heat inflows or outflows through the valve stem between the valve operating part and the fluid, and consequently entailing a problem wherein the fluid alters its temperature.